The present invention generally relates to methods and systems for improving electrical load regeneration of an aircraft and, more particularly, to methods and systems that may return regenerated power to the distribution bus of an aircraft for reuse.
Power electronics for aerospace applications play a significant role in the modern aircraft and spacecraft industry. This is particularly true in the area of more electric architecture (MEA) for aircraft and military ground vehicles. Some aircraft already utilize MEA, including primary and secondary flight control.
Those aircraft that utilize MEA have electrical loads with power demands that are substantially transient in nature. The transients typically last less than a second and have a repetition rate in the range of a fraction of a Hertz. Significant regeneration transients are also anticipated. Large current spikes from the power source are required for vehicle surface control actuators when operating in quadrants I and III (motoring). Large current spikes are regenerated when operating in quadrants II and IV (generating). A schematic of the surface control actuators four-quadrant operation is shown in FIG. 1.
These electrical loads, such as electromechanical and electro-hydrostatic flight control actuators, can demand high peak power, potentially driving the size of an aircraft's electrical power generation and distribution systems. A method of satisfying this peak demand without unduly increasing the size of the electrical system is desirable. The mechanical demand of the actuators results in a high-amplitude, short-duration power or current exchange between the actuator control power electronics and the DC supply bus. This power/current exchange is bidirectional, resulting in a need to accommodate regenerative power.
The typical approach, as shown in FIG. 2, has been to use shunt regulation in an actuator controller 100 to locally dissipate the regenerated power. When the actuator load is aiding (the signs of torque and speed are opposite), the controller must be able to brake the load. This is achieved by removing the energy from the actuator system. In these cases, the electrical machine acts as a generator. The controller provides a variable electric load to control the energy being removed from the mechanical system. The electrical load dissipates the energy as heat. Circuitry and control are provided to detect this condition and direct the power from the motor into an aiding load resistor 102.
This is an inefficient approach because it typically requires cooling (e.g., of load resistor 102) to dissipate the energy. The power is wasted, and the size of the actuator controller is increased to satisfy the necessary cooling requirements. The regenerated power could be stored to specially designed devices, such as batteries, super capacitors, or flywheels. However, substantial penalties will be paid in the areas of reliability, weight, volume and cost due to the substantial increase in complexity.
As can be seen, there is a need for a novel method and system of improved aircraft load regeneration that results in improved performance without requiring shunt regulation and without the necessity for additional cooling.